Spark plug



Nov. 20,1928.

P. MILLER SPARK PLUG Filed March 23, 1927 Paul 'D Tiller 3 mute o I 3mm?Patented 2 0,

UNITED STATES PATENT OFFICE.

PAUL MILLER, 01 PITTS IOWN, NEW YOBK, ASSIGNOR F ONE-THIRD TO FREDERICKC. CLAESSENS, OF TROY, NEW YORK.

- SPARK PLUG.

Application fled March 23,1921. serial in. 177,809.

. The present invention relates to spark plugs, and the primary objectof the invention is to provide an improved spark plug embodying featureswhereby an intensified spark will be created between the electrodes ofthe plug for insuring ignition of the explosive charge in the enginecylinder with which the plug is associated.

A'further object of the invention resides in the provision ofa sparkplug embodyin a pair or more electrodes so formed an related one to theother that when the plug is firing, a divided spark bridging the gapbetween the spaced electrodes will be united at one of the electrodesfor reinforcing of the spark and producing an extremely hot spark.

Aifurther object of the invention resides in the provision of a sparkplug embodying a central electrode having a firing point or portionwhichmay be readily rotated in the insulating core of the plug for exposingnew firing surfaces, and which electrode when in either of its adjustedpositions will,

present firing surfaces each being spaced an equal distance from thefiring point of the grounded electrode of the plug.

A still further object 'of the invention resides in the provision of aspark plugof the class described whichmay be economieally constructed,and one wherein the improved central electrode for the producing of adivided spark may be readily associate with existing types of sparkplugs of knock down construction.

Other objects and advantages of the invention will be apparent duringthe course of the following detailed description, taken in connectionwith the accompanying drawing forming a part of this specification andin which 'drawing Figure 1 is a central longitudinal section through aspark plug embodying the improved features of the present invention.Figure'2 is an end elevation of the inner manner in which the dividedspark is produced between the electrodes of the lug,

Figure 3 isa' side elevation of the mnerend of the central electrode andillustrating end of the plug and clearly illustrating the the specificconstruction and arrangement of the firing portions of the electrode.

Figure 4 is a side elevation of'the inner I end of the central electrodeand illustrating nate corresponding parts throughout the several views,5 designates the metal shell of the spark plug in which is mounted aninsulating core 6, and which core is retained in position by means of 'apacking nut 7 having threaded engagement in the outer end of the metalshell 5. The core 6 and which may be formed of any suitable insulating 9material is provided with a centrally dis-x posed bore 8 having itsinner end enlarged for providing a pocket 9 and forming an abutment orshoulder 10. Carried by the inner end of the metal shell 5 is a groundelectrode 11 of substantially L-shape in formation and arranged with thefiring point 12 thereof extending inwardly toward the axial center ofthe bore 8 Rotatably and slidably fitting snugly within-the bore 8, andhaving its terminals projecting past the inner and outer endsof thebore, is a central electrode 14 having a w cylindrical stem portion 15the outer end of which projects past the outer end of the core 6 and isthreaded as at 16. Formed at the inner end of the cylindrical stemportion 15 is an annularly projecting shoulder or collar 18 which isintended to be re eived in the pocket 9 for limiting outward movement ofthe electrode 14 when properly positioned within the bore 8. Below thecollar 18*is formed a firing portion 20 of special and novel formationfor cooperating with the electrode 11 in a manner for producing a.divided spark concentrating at the firing point 12 of the electrode 11.

This firing portion 20 and which preferably constitutesan integral partof the stem portion 15, embodies a pair or more of sub-. stantiallv flattines 21 and 22 which form inde ndent firing points for the inner end oft e electrode. 14. These firing tines 21 mo clearl illustrated in Figure4 for dispos in 't e terminals ofthe tines' to opposite si es of thelongitudinal axis of the electrodes. Each inner or confronting ed e ofthe tines are provided with teeth 24 an it is preferred that' the teethof one tine align with the teeth of the companion tine. The'se tines 21and'22 aside from having their flat faces 23 extending away from oneanother toward the terminals of the tines, also have 21 and 22 will'roduce .a 'V-sha their outer edges 25 extending in diverging relationfrom the axial center of the electrode-toward the free ends of thetinesas clearly illustrated in'Figure 3. I

. A suitable packing 26 is preferably disposed between the collar 18 andshoulder 10 for sealing the inner end of the bore 8, and after insertionof the electrode 14 into the bore 8' from the. inner end of the core 6'a retaining nut 27 is threaded upon the threaded extension 16 intoengagement with suitable lock washers 28 for retaining the electrode 14in osition and against rotation within the insulating core 6. A suitableterminal nut 29 may be threaded upon the outer end of the extension 16for attachment of a suitable conductor, and this may further serve asalocking means Figure 2, it will beobserved that the convex w .-surfaceof ,the tine 22'and the inner corrud gated edge of the tine 21'will bedis 1n confronting relation with the terminal surface and corrugated edare spaced equi distant from the termin y ,of the point 12. This equalspacing of portions ofthe tines withftheindivi ual sparks meeting at thefiring point 12. Byrotating the electrode.

- 14 for a one-half turn, the convex surface of. he tine '21 and theinner corru ated edge of the tine 22 will be disposed in firing relatioitotzhe firing point 12 of the electrode 11. The spacing betweentheterminal of the firingepoint 12 and the tines 21 and 22 may alsovaried b the positioning of fiackings 26 of different t 'cknessesbetween t e collar 18 and shoulder 10 for limiting outward movement ofthe electrode when secured in positionb meansof-the nut 27'.

From. apparent that an improved and novel type 0' spark plug has beenprovided wherein e following claims.

ing independent firing tines extending .and a central electrode d sparkgatedinner ed e.

.at its inner end with a pair of tion in the core, e foregoingdescription it will be electrodes are so formed and so related that adivided spark unites at'one of the electrodes for producing aconcentrated firing spark, andone wherein the central electrode specialformation is readily renewable and adjustable with respect to thegrounded electrode of the plug.

Changes in detail may be made to the specific form of the inventionherein shown and described, without'departing from the spirit of theinvention .or the scope of the I claim: I

1. In. a spark plug, the combination of 1 an insulating core having acentral bore,a core supporting. shell carrying a ground electrode atitsmner end, a central electrode fitting in saidbore and havingindependent firing portions, rovided at its inner end extendlng 1niverging" relation to one another, and means for adjusting the centralelectrode lon 'tudinallyof the core for adjustment oft e independentfiring portions toward andaway from the ground electrode. 2.. In a sparkplug, the combination of an insulating core having a central bore a coresupporting shell carrying a un electrode at its inner end, a centreelectrode including a stem portion rotatably mounted, in said bore andhaving a divided firing portion provided at its inner end form- 111divergent relation from thestem portion and curved longitudinally inopposite directions, and means for retaining the central electrode aainstrotation with 11, int on each surface 0 the tines spaced a likedistance from a single point on the surface of the ground electro e.

3. In a spark plug, the combination of an insulating core, a coresupporting shell carrying a ground electrode at its inner end,

carried by the core having a divided inner end forming independentfiring tines extending invdivergent relation and positely curvedlongitudinally and each ing formed with a corru- 4. In a spar plug, thecombination of an insulating core ha a central bore, a core supportingshell having a und electrode carried by its inner en a central electrodeincluding a stem rtion rotatably and slidably fitting. in saidreandprovided substantially fiat firing ortions extending in divergentrelation an each provided with a'corrugzted inner ed e, said flat firingportions-also arcuat'e' longitudinally 1n op o site directionswherebywhen the electro e'is inposione. corru ated inner edge the convex,surface 0 thecom. anion III firing portion may be dis equitant from saidground enema means for l retainin the central electrode against rotationan longitudinal shifting within said core.

5. A central electrode for spark plugs provided with ground electrodesat their inner ends, comprising a cylindrical stem portion having athreaded outer end and an annular collar at its inner end, and a firingportion flattened and split longitudinally at the inner end of the stemfor forming a 1 pair of substantially flat tines, said tines each havingteeth formed at their inner edges and oppositely arcuated longitudinallywith the terminals of the tines extending to opposite sides of the stemportion.

PAUL MILLER.

longitudinal axis of said 15

